Outboard motor exhaust system



Oct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet1 Filed May 9, 1963 INVENTOR. RICHARD C. STALLMAN ATTORNEYS Oct. 5, 1965R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet 2 Filed May9, 1963 V IY/IIIIIIIIIIZI I I 1 4 n v I i F/G. 7 RICHARD g ffmmATTORNEYS Oct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4Sheets-Sheet 3 Filed May 9, 1965 INVENTOR. RICHARD C. STALLMAN ATTORNEYSOct. 5, 1965 R. c. STALLMAN OUTBOARD MOTOR EXHAUST SYSTEM 4 Sheets-Sheet4 Filed May 9, 1963 F/G /Z Ill III) INVENTOR RICHARD C. STALLMAN UnitedStates Patent 3,209,534 OUTBOARD MOTOR EXHAUST SYSTEM Richard C.Stallman, 392 De Anza Ave, San Carlos, Calif. Filed May 9, 1963, Ser.No. 279,206 4 Claims. (Cl. 60-3554) This invention relates generally toan exhaust system for outboard motors and more particularly to anexhaust system for outboard jet motors.

In my United States Patent No. 3,082,732, there is described a water jetpump adapted to be attached to outboard motors to form outboard jetmotors.

Early exhaust silencers for outboard motors exhausted to the atmosphereand utilized a series of baflles which served to break up the soundwaves. In so doing, however, they caused gas flow restriction and gaverise to back pressure. The more efficient the silencing of the system,the higher the back pressure. In high speed two-cycle engines ascompared to four-cycle engines, sound suppresion becomes more diflicultand called for higher gas restrictions with its attendant higher backpressures. High increased back pressure lowered the engine efliciencyand output power. Recently, outboard motor exhaust gases have beendirected under water into the slip stream behind the propeller. Theexhaust gases are mixed with the water so that the water absorbs thesound waves to silence the exhaust system.

It is a general object of the present invention to provide an improvedengine exhaust system.

It is another object of the present invention to provide an improvedengine exhaust system for use with outboard water jet motors.

It is a further object of the present invention to provide an exhaustsystem in which the water jet stream from the motor aspirates theexhaust gases and absorbs the sound waves as the exhaust gases are mixedin the jet stream.

It is still a further object of the present invention to provide anengine exhaust system in which the exhaust manifold outlet cooperateswith the water jet stream from a Water jet motor to aspirate and silencethe exhaust noises.

It is a further object of the present invention to provide an outboardjet motor including a reversing gate which cooperates with the manifoldfor silencing during reverse operation.

It is a further object of the invention to provide an outboard jet motorin which the exhaust manifold not only cooperates with the jet stream tobe aspirated thereby but also serves as a vane to direct the jet stream.

These and other objects of the invention will become more clearlyapparent from the following description when taken in conjunction withthe accompanying drawmgs.

Referring to the drawing:

FIGURE 1 shows a portion of a boat and outboard water jet motor;

FIGURE 2 is a side elevational view, partly in section, of a water jetmotor incorporating the exhaust system of the present invention;

FIGURE 3 is a top view of the water jet motor of FIG- URES 1 and 2;

FIGURE 4 is a partial sectional view taken along the line 4-4 of FIGURE3;

FIGURE 5 is a partial sectional view taken along the line 5-5 of FIGURE3;

FIGURE 6 is a partial sectional view taken along the line 6-6 of FIGURE3;

FIGURE 7 is a sectional view taken along the line 7-7 of FIGURE 3;

3,209,534 Patented Get. 5, 1965 FIGURE 8 is the rear portion of theoutboard jet motor of FIGURES 1-7 with the reverse gate disposed in thereverse position;

FIGURE 9 is a view showing the rear of the outboard jet motor shown inFIGURE 8;

FIGURE 10 shows a view of the rear portion of a jet motor having amodified exhaust manifold;

FIGURE 11 is a sectional View taken along the line 11-11 of FIGURE 10;

FIGURE 12 is a top view, partly broken away, to show the internalportions of the outboard jet motor shown in FIGURE 10; and

FIGURE 13 is a rear view of the outboard jet motor as shown in FIGURE 12and rotated to the vertical.

In FIGURE 1, an outboard jet motor 11 is shown attached to a boat 12 inthe normal manner with suitable clamps 13. The motor 11 includes aninternal combustion engine portion 14 which drives a jet water pump 16which may be of the type described in US. Patent No. 3,082,732. It isobserved that the jet pump replaces the standard outboard motor gear boxand propeller section. Water enters the jet pump through the intakesection 17, flows through the casing 18, is collected by the recuperator19 and expelled to the rear through jet nozzle 20.

The intake section 17 includes an upper portion 21, FIGURE 2, which isconnected to the recuperator section and which serves to house a mixedflow impeller 22. The impeller is driven by a shaft 23 which may besplined or the like at its upper end (not shown) to engage the powerhead of the internal combustion engine in a normal manner.

The impeller 22 is provided with helically arranged blades or vanes 10formed integral with a hub 15. The outer edges of the vanes define asurface of revolution which matches the taper of the cooperating portion21 of the intake section. When the impeller is driven by the engine,water is pulled into the pump casing and forced into the recuperatorsection 19. The centrifugal forces due to the spinning of the impellerserve to drive the water into the spiral-shaped recuperator section,shown more clearly in FIGURE 3. The water then flows through the jetnozzle designated generally by the numeral 27 in FIGURE 3. Therecuperator, in the form of an ever increasing spiral, gathers thespinning water from the impeller in an orderly fashion and directs itinto the nozzle 20. The jet nozzle is provided with one or more vales41, FIGURE 2, which serve to guide the jet stream in the nozzle so thatit is expelled from the small end 42 of the nozzle in an hydraulicallyel'ficient manner.

The shaft 23 is supported in a bearing 32 carried in the bearinghousing. The bearing housing is suitably attached to the recuperator.

Referring more particularly to FIGURE 2, there is shown the lowerportion of the exhaust chamber of manifold 36 of the internal combustionengine.

There is formed about the recuperator 19 and nozzle 20 an exhaustmanifold. Referring to the figures, the manifold is formed by anintegral casting which, together with the recuperator and nozzle, formthe chamber.

The exhaust gases in the outboard motor chamber travel downwardly intothe manifold in the recuperator casting, as indicated by the arrows 44,into the exhaust manifold. The exhaust manifold continues in a rearwarddirection along one side of the nozzle to a point near its end. Themanifold is then wrapped around the nozzle, in the form of a shroud, toencircle approximately the upper half of the nozzle. The shape andextent of the exhaust manifold can best be seen by an examination of thesectional views of FIGURES 4 through 7.

manifold as described above.

The exhaust gases are then directed outwardly, as shown more clearly inFIGURE 2 by the arrow 49, Where they meet the water jet stream,represented by the plurality of arrows 51. It is observed that the waterjet completely covers the open end of the manifold. The high velocitywater jet stream flowing past the exhaust manifold opening will serve toaspirate the exhaust gases to lower the pressure in the exhaustmanifold. The back pressure in the engine is below normal back pressurewhich would be obtained if the engine were opened directly to thesurrounding atmosphere. This increases the efiiciency of the motor.Furthermore, the sound or shock waves of the engine exhausts areabsorbed in the water stream and the engine is efficiently silenced.

A reverse gate may be suitably pivoted at the nozzle of the integralbosses 61, FIGURE 8, formed on either side thereof. The gate is pivotedabout the point 62 whereby it may be moved to the position shown in FIG-URE 1 for forward travel with the jet stream cooperating with theexhaust manifold as previously described. To reverse the direction ofthe thrust, the gate is raised whereby it covers the jet nozzle as shownin FIGURE 8. The water jet stream then engages the reversing gate toreverse its direction, and consequently the thrust direction. Thereversing gate is so formed as to have an annular ring 72 at the upperportion thereof which cooperates with the shroud of the exhaust manifoldto reduce the exhaust passage to form a restricted passage 73. Thisserves to silence the engine in operation of the motor in reverse. Therestricted exhaust passage also results in increased back pressure;however, in general, maximum efficiency is not required when operating aboat in reverse.

It is further observed that the reverse gate is pivoted about a pointwhich is above its geometric center 78, whereby the water jet streamprovides a component of force which acts to rotate the gate upwardly tomaintain the gate in its reverse position.

In order to shift out of reverse, the engine is brought down to a slowspeed or to idle, thus reducing the water pressure, and the gate is thenshifted to the disengaged position. A small spring detent (not shown) issuflicient to maintain the hand lever 77 in its forward position. Thisis due to the fact that in the forward position, the control rod 74center line coincides with the lever pivot 77 center line. Thisessentially locks the gate in its forward position whereby a smalldetent may be employed.

In the embodiment just described, it is seen that in reverse, theexhaust gases are not mixed in the jet stream but rather flow through arestricted opening which suppresses the sound waves. In the embodimentshown in FIGURES -13, there is provided an exhaust manifold 82 which iscontinuously in the water jet stream whether the boat is operated in theforward or reverse direction. This exhaust manifold serves also thefunction of guiding the water flow in the nozzle.

Referring more particularly to the figures, FIGURE 10 is a sideelevational view showing a modified nozzle; FIGURE 11 is a view takenalong the line 11-11 of FIGURE 10; FIGURE 12 is a top view, partlybroken away to show the exhaust outlet; and in FIGURE 13, there is showna rear view.

The exhaust manifold includes a portion 81 which cooperates to receivethe gases from the engine exhaust The exhaust manifold 82 projectsdownwardly into the nozzle and provides an opening such that the exhaustgases travel down into the exhaust manifold to the outlet which is inthe jet stream.

If desired, a splash guard 86 may be provided for preventing splashingof water when the boat is shifted from manifold outlet. This providesmixing and aspiration of the exhaust gases while operating the boat ineither forward or reverse.

Thus, there has been provided an improved exhaust system for outboardwater jet motors. The sound waves are so directed as to be absorbed bythe jet stream which cooperates with the exhaust manifold to provideaspiration of the exhaust gases to lower the back pressure.

I claim:

1. In an outboard jet motor of the type including an internal combustionengine connected to drive a water pump which jets the water through ajet nozzle comprising a pump having an intake, a mixed flow impellerserving to pump the water within the same, a spiral recuperator servingto recuperate the water being pumped by the mixed flow impeller andterminating in a nozzle which forms the jet stream, a means forming anexhaust manifold enveloping a portion of said nozzle, one end of saidexhaust manifold serving to receive exhaust gases from the engine, andthe other end of said exhaust manifold opening toward the jet stream andpositioned to be closed by the jet stream whereby the exhaust gases areaspirated from the manifold and entirely mixed with the jet stream.

2. In an outboard motor of the type including an internal combustionengine connected to drive a water pump which jets the Water through ajet nozzle comprising a pump having an intake, a mixed flow impellerserving to pump the water into said intake, a spiral recuperator servingto recuperate the Water being pumped by the mixed flow impeller andterminating in a nozzle which forms a jet stream, means forming anexhaust manifold enveloping a portion of said nozzle, one end of saidexhaust manifold serving to receive exhaust gases from the engine, theother end of said exhaust manifold being positioned to engage and beclosed by the jet stream whereby the exhaust gases are aspirated fromthe manifold and mixed with the jet stream, a cup-shaped reversing gatepivotally mounted on said nozzle and adapted to have a first position inwhich the jet stream is free to flow past the same, and a secondposition in which the reversing gate engages the jet stream andrestricts said other end of the exhaust, said reversing gate beingmounted off center whereby the Water pressure in the reversed positionserves to lock the gate in said position.

- 3. An outboard jet of the type adapted to be attached to an internalcombustion engine comprising a jet nozzle, a water pump for pumpingwater into said nozzle to form a water jet stream, an exhaust manifoldhaving one end arranged to receive the engine exhaust gases and anotherend disposed to exhaust the same, said other end being formed by ashroud which surrounds a portion of said nozzle to form an opening whichopens towards the jet stream and which is positioned to be closed by thejet stream, said jet stream serving to aspirate the exhaust gases fromsaid other end of said manifold and mix the same entirely in the jetstream.

4. An outboard jet of the type adapted to be attached to an internalcombustion engine comprising a jet nozzle, a water pump for pumpingwater into said nozzle to form a water jet stream, an exhaust manifoldhaving one end arranged to receive the engine exhaust gases and anotherend disposed to exhaust the same, said other end being formed by ashroud which surrounds a portion of said nozzle to form an opening whichopens towards the jet stream and which is positioned to be closed by thejet stream whereby the jet stream aspirates the exhaust gases from saidother end of the manifold and mixes the same in the jet stream, acup-shaped reversing gate having a first position in which it does notengage the jet stream and a second position in which it engages the jetstream to reverse the direction of the same and at the same timecooperates with said other end of the exhaust manifold to provide arestricted passage, said cup-shaped reversing gate including an annularring portion which cooperates with said other end of the exhaustmanifold to form the restricted passage.

References Cited by the Examiner UNITED STATES PATENTS 6 3,090,346 5/63Burgin 60-3555 3,105,353 10/63 Schulz 60-3555 3,111,108 11/63 Trotter60-3554 FOREIGN PATENTS 932,548 11/ 47 France.

877,982 9/61 GreatBritain.

SAMUEL LEVINE, Primary Examiner.

3. AN OUTBOARD JET OF THE TYPE ADAPTED TO BE ATTACHED TO AN INTERNALCOMBUSTION ENGINE COMPRISING A JET NOZZLE, A WATER PUMP FOR PUMPINGWATER INTO SAID NOZZLE TO FORM A WATER JET STREAM, AN EXHAUST MANIFOLDHAVING ONE END ARRANGED TO RECEIVE THE ENGINE EXHAUST GASES AND ANOTHER,END DISPOSED TO EXHAUST THE SAME, SID OTHER END BEING FORMED BY A SHROUDWHICH SURROUNDS A PORTION OF SAID NOZZLE TO FORM AN OPENING WHICH OPENSTOWARDS THE JET STREAM AND WHICH IS POSITIONED TO BE CLOSED BY THE JETSTREAM, SAID JET STREAM SERVING TO ASPIRATE THE EXHAUST GASES FROM SAIDOTHER END OF SAID MANIFOLD AND MIX THE SAME ENTIRELY IN THE JET STREAM.